In many animals, bacteria modulate nutrition, gut development, immune system maturation, and longevity. In Drosophila melanogaster, bacteria enhance longevity but their effects on vertebrate aging are unknown. The long-term goal of this proposal is to determine the role that bacteria play during the aging process in the well-characterized Drosophila model system. Several lines of evidence suggest that these studies may also provide a basis for the mechanism by which bacteria affect longevity in humans, as well as tools for promoting human longevity. First, as all animals evolved in the presence of bacteria and most are colonized by them, it is likely that conserved methods for detecting and modulating bacterial flora exist across species. In addition, genes involved in the regulation of aging are conserved across diverse phyla and some of these, when mutated, produce both long life, and altered responses to bacteria. Furthermore, genes regulating both the fly immune system and human innate immune system are highly similar suggesting that pathways involved in the sensing and interaction with bacteria are highly conserved. Characterization of DJ817, a novel mutation that extends Drosophila longevity only when bacteria are present, will be performed to specifically address the role of bacteria in aging. Initial experiments will identify the gene involved via excision analysis as well as RNA interference-mediated assays to eliminate the gene function in subsets of tissues in which it is normally expressed in order to determine the spatial-temporal requirement of the gene. Further characterization will include identifying and characterizing the bacteria involved in longevity extension by using metabolic fingerprinting, a substrate utilization assay that measures metabolic capacity based upon the ability of bacteria to utilize a panel of different carbon substrate sources. Beneficial bacteria and their components will be identified and screened in assays based upon the observation that bacteria can increase the rate of development in flies by 50% relative to flies lacking bacteria. [unreadable] [unreadable] [unreadable] [unreadable]